Illinois Natural History Survey - University of Illinois

DRIFTLESS AREA 

Bluffs above the Mississippi River in the Driftless Area RRA, photo by Mike Jeffords, INHS Algific slopes are north-facing rocky slopes that retain subsurface ice through most of the year. In Illinois they occur only in the Driftless Area. The cold microclimate created on the surface of the slope supports relict northern and Pleistocene biota, including many endangered, threatened, and rare species.

Map of Site
Land Cover Map of Site

 

SIZE: 191,814 acres 300 square miles

LOCATION: Northwestern Illinois on the Mississippi River; Jo Daviess, Carroll and Whiteside counties.

The Driftless Area RRA occupies a physiographically unique part of the state that escaped Pleistocene glaciation. The area is characterized by rolling hills and a dis sected pattern of wooded ridges and includes such promi nent features as canyons, ravines, bluffs, and palisades. Some of the flora and fauna are distinctive and unique in the state, including several plant species which are northern species or preglacial and interglacial relicts.

LANDCOVER: The Driftless Area RRA has the highest percentage of grassland of all the sites (37%). (The grassland category in this publication includes pastures, hayfields, idle fields, rural-road and railroad rights-of-way, and prairie remnants.) The site is one-fourth wooded22% upland woods and nearly 6% bottomland woods. Much of the woodland is found on ridges. Twenty percent of the area is cropland; this is one of the few nonurban RRAs where cropland is not the predominant landcover type.

NATURAL AREAS: There are 19 Natural Areas in this RRA. This site contains more Natural Area acreage than any other RRA (30,556 acres, 16% of the site area). The Savanna Army Depot accounts for approximately 14,000 acres; otter habitat and Spring Lake, a large lake associated with the Mississippi River, are other large Natural Areas.

BIOLOGICALLY SIGNIFICANT STREAMS: This site contains 22.4 miles of streams identified as biologically significant.

HERITAGE SITES: There are 109 Heritage occurrences in the Driftless Area RRA: three significant community types, 30 plant species, 20 animal species, and three rookeries.

STATE AND FEDERAL LAND: Mississippi Palisades State Park is lo cated in this RRA as well as one state fish and wildlife area. This site has the second highest percentage of area in federal ownership (21% of the area; 40,612 acres). Federal lands are the Upper Mississippi Wildlife and Fish Refuge (26,579 acres) and the Savanna Army Depot (14,033 acres). See sidebar on page 16.

NATURE PRESERVES: There are four Nature Preserves in this RRA. Significant features include sand prairie, sand dune and blowout, cliff, hill prairie, and seep springs.

NATURAL DIVISIONS: Nearly three-fourths of the Driftless Area RRA is comprised of the Wisconsin Driftless Division. This RRA is the only site that includes this division; 37% of

The Savanna Army Depot is currently being decommissioned as an ordance storage facility. It covers approximately 20 square miles and includes bottomland, oak forest, wetlands, upland sand prairie, and habitat for 32 endangered or threatened plants and animals. Approximately 9,000 acres will be transferred to the U.S. Fish and Wildlife Service for addition to the Upper Mississippi River Wildlife and Fish Refuge.

SUMMARY OF SITE CHARACTERISTICS: SIZE, BIOLOGIC RESOURCES, AND PUBLIC LANDS 

Total Acreage 191,814
Natural Areas
    Acreage
30,556
    Number
19
Biologically Significant Stream Mileage 22.4
Natural Heritage Sites 109
State Land
    State Parks
1
    State Conservation Areas
0
    State Forests
0
    State Fish & Wildlife Areas
1
Acreage 3,354
Percentage of RRA 1.7
Federal Land
Acreage 40,612
Percentage of RRA 21.2

 

LANDCOVER Acres % of RRA
Upland forest 41,587.13 21.68
Bottomland forest 10,643.35 5.55
Wetland- nonforested 1,119.55 0.58
Grassland 71,811.77 37.44
Cropland 37,603.67 19.60
Urban/Built-up 2,710.36 1.41
Water 26,338.33 13.73
Total 191,814.16 99.99

 


 

ILLINOIS NATURAL AREAS INVENTORY SITES Acres
Ayers Sand Prairie 29
Blackhawk Otter Habitat 3,625
Dixon Creek North Geological Area 2
East Dubuque Geological Area 5
Hanover Bluff 164
Jo Daviess County Otter Habitat 6,550
Mississippi Palisades 412
Mississippi Palisades Geological Area 2
Palisades Stickseed Site <1
Pilot Knob Geological Area 1
Princess Mine Algific Slope 154
Redroot Site 1
Rice Algific Slope 49
Royal Princess Geological Area 3
Savanna Army Depot 14,323
Savanna South Railroad Prairie 61
Spring Lake 4,913
Thomson-Fulton Sand Prairie 262
Wise Lake Geological Area 2

 

BIOLOGICALLY SIGNIFICANT STREAMS Miles
Apple River, Wolf Creek to Mill Creek 12.0
Menominee River 5.1
Mississippi River, rm 545-550, Carroll Co. 5.3

 

NATURAL HERITAGE CATEGORIES
Communities Occurrences Types/Species
    Wetland
1 1
    Prairie
2 2
Threatened and Endangered Animals
    Bird
27 11
    Fish
3 2
    Mammal
15 2
    Reptile
3 2
    Crustacean
1 1
    Mollusk
2 2
Threatened and Endangered Plants
    Plant-Dicot
29 21
    Plant-Gymnosperm
1 1
    Plant-Monocot
11 7
    Plant-Fern/Fern Ally
6 1
Geological Feature 5 1
Other
    Rookery
3 1

 

STATE AND FEDERAL LAND
State Parks Acres
    Mississippi Palisades
2,350
State Conservation Areas 0
State Forests 0
State Fish and Wildlife Areas
    Witkowsky
1,004
Federal Land
    Savanna Army Depot
14,033
    Upper Mississippi River F&W Refuge
26,579

 


 

NATURE PRESERVES Acres
Ayers Sand Prairie 23
Hanover Bluff 390
Sentinel 51
Thomson-Fulton Sand Prairie 83

 

NATURAL DIVISIONS Acres in RRA % of RRA % of Division
Wisconsin Driftless 135,938 72.6 37.0
Major Water Bodies 21,236 11.3 1.9
Up. Mississippi R and Illinois R Bottomlands 18,658 10.0 1.6
Illinois R and Mississippi R Sand Areas 11,501 6.1 3.0


Illinois Natural History Survey

1816 South Oak Street, MC 652
Champaign, IL 61820
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cms@inhs.illinois.edu

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